He added: "Everybody - the 25,000 staff and volunteers - are compromised by this, the hundreds of thousands of people who support Oxfam every month are compromised by this, and to everybody I apologise.

"What I'm apologising for is that nine Oxfam staff behaved in a way that was totally unacceptable and contrary to our values, and that led much more responsible staff to make decisions which are now seen by some as being marginal or inappropriate.

"But I'm not apologising for the fact that Oxfam continued its work in Haiti."

Image:Estimates vary but around 220,000 people were killed in the Haiti disaster

Estimates vary but around 220,000 people were killed in the Haiti disaster and millions left homeless in a country where more than half of the population live in poverty.

Prostitution is illegal in Haiti.

Mr Goldring added: "There is not a single organisation in which there has not been sexual abuse and exploitation and Oxfam is certainly no worse than most other international organisations and actually has tried in many ways to be better."

The charity said it investigated the allegations in 2011 and perpetrators were all sacked or resigned.

However, some went on to senior roles at other charities that were not informed of their reasons for leaving Oxfam, it was reported.

Image:Millions of Haitians were affected by the 2010 earthquake

Mr Goldring added that a safeguarding team had been set up to improve the quality of reporting investigations, as well as a "whistle-blowing line".

He added: "If we can be part of helping with references or cross-checking then we'll play an active part in that because I've seen the amazing work that Oxfam is doing in the Congo, Syria, in Bangladesh, Yemen, in places other people simply won't go.

"I want to protect and preserve that."

There had been other incidents since 2011, he said, but "nothing on the scale of this severity".